title: Allyl 2-(2,2-dimethyl-3a,6a-di-hydro-furo[3,2-d][1,3]dioxol-5-yl)-4-oxo-4H-chromene-3-carboxyl-ate.
abstract: In the title compound, C20H18O7, the dioxolane ring adopts an envelope conformation with the dimethyl-substituted C atom as the flap, and its mean plane makes a dihedral angle of 73.25 (2)° with the pyran ring mean plane. The furan ring makes dihedral angles of 67.43 (12) and 6.20 (11)° with the mean plane of the dioxolane and pyran rings, respectively. The O atom attached to the pyran ring deviates by 0.0219 (2) Å from its mean plane. In the crystal, mol-ecules are linked via C-H⋯O hydrogen bonds, forming chains along [010] and enclosing R 2 (2)(9) loops. They stack along the a axis with π-π inter-actions involving the 4H-chromene units [centroid-centroid distances of 3.6389 (13) and 3.6555 (13) Å]. The terminal CH2=CH- atoms of the allyl acetate group are disordered over two sets of sites with a refined occupancy ratio of 0.717 (6):0.283 (6).
authors.affiliation: Centre of Advanced Study in Crystallography and Biophysics, University of Madras, Guindy Campus, Chennai 600 025, India.
authors.forename: Zeenat
authors.initials: Z
authors.lastname: Fatima
authors.forename: Thothadri
authors.initials: T
authors.lastname: Srinivasan
authors.forename: Jonnalagadda Naga Siva
authors.initials: JN
authors.lastname: Rao
authors.forename: Raghavachary
authors.initials: R
authors.lastname: Raghunathan
authors.forename: Devadasan
authors.initials: D
authors.lastname: Velmurugan